Vehicles, such as aircraft, marine vehicles, ground vehicles and spacecraft, typically use omnidirectional antennas at long wavelengths for long-range communications. Because these omnidirectional antennas are low gain, radio waves (e.g., a radio signal) transmitted by these antennas can be easily detected and/or intercepted due the indiscriminate radiation pattern of the radio waves. Therefore, high-directional antenna gain may be desirable for long-range communications.
High-gain antenna directionality may be accomplished using various techniques, such as utilizing a phased array of antennas, employing a dish antenna or horn antenna, or utilization of a large aperture directional antenna. However, a directional antenna at longer wavelengths is difficult to implement using traditional array, dish, or aperture techniques.
Antenna beam steering is typically accomplished using electronic weighting of antenna elements in a phased array or by mechanically steering the antenna, for example, using a gimbal, to provide a radio wave beam in a desired azimuth and elevation. However, use of such large aperture antennas and associated electronics and/or mechanical gimbals may be precluded from use on aerospace vehicles (e.g., aircraft) due to size and or weight.
Additionally, because antennas include delicate components that may be damaged when exposed to ambient conditions, antennas are often housed in radomes that prevent physical matter, such as debris, precipitation, moving air and the like, from coming into direct physical contact with antenna components. As such, a radome functions as a physical barrier to potentially damaging matter, while still permitting the propagation of electromagnetic radiation, particularly radio waves, to and from the protected antenna. Radomes are especially important to aircraft due to the aerodynamic drag and environmental sensitivity of antennas and electronic components.
Accordingly, those skilled in the art continue with research and development efforts in the field of high-gain directional antennas and radomes.